kdump-lib-initramfs.sh: make it POSIX compatible
    
    upstream: fedora
    resolves: bz2003832
    conflict: none
    
    commit 5debf397fef03931c0736d473a55ebcf6dc08380
    Author: Kairui Song <kasong@redhat.com>
    Date:   Tue Sep 14 03:04:08 2021 +0800
    
        kdump-lib-initramfs.sh: make it POSIX compatible
    
        POSIX doesn't support keyword local, so add double underscore and prefix
        to variable names, and reduce variable usage, to avoid any variable name
        conflict.
    
        Also reformat the code with `shfmt -s -w kdump-lib-initramfs.sh`.
    
        Signed-off-by: Kairui Song <kasong@redhat.com>
        Acked-by: Philipp Rudo <prudo@redhat.com>
    
    Signed-off-by: Tao Liu <ltao@redhat.com>